Final answer:
Check-in promotions are a true and effective way for businesses to engage with customers by offering personalized deals based on past purchases, thereby enhancing customer loyalty and sales.
Step-by-step explanation:
The statement 'Use check-in promotions to alert customers about special deals based on their past purchases' is True. Check-in promotions are a marketing strategy that businesses employ to engage with their customers by providing them with personalized offers. By tracking past purchases, businesses can tailor these promotions to individual customers and incentivize them to visit the store or website to take advantage of these special deals. Providing customers with relevant offers can increase customer loyalty and drive sales.